## Facts

- Maryland Heights Leasing, Inc. (Maryland) owned approximately six acres of land and leased the property to Bennett Paper Corporation (Bennett) for business operations.
- A plant owned and operated by Mallinckrodt, Inc. (Mallinckrodt) bordered the leased property on three sides.
- Mallinckrodt’s plant produced nuclear and radioactive medical pharmaceuticals and supplies.
- Mallinckrodt operated two cyclotrons at the site to convert non-radioactive materials into radioactive materials.
- Maryland and Bennett alleged that low-level radiation emissions from Mallinckrodt’s operations migrated onto their property.
- The petition sought damages for alleged injury to the property and interference with its use, pleading four counts labeled nuisance, negligence, trespass, and engaging in ultrahazardous activities.
- Mallinckrodt moved to dismiss under Missouri Rule 55.27(a)(1) and (6), arguing (1) the circuit court lacked subject-matter jurisdiction because the claims were barred by federal preemption and the political question doctrine, and (2) the petition failed to state a claim.
- The trial court granted the motion and dismissed the petition; Maryland and Bennett appealed.

## Issues

1. Whether federal nuclear law preempts Missouri common-law tort claims seeking damages for alleged property harm caused by low-level radiation emissions from a federally regulated facility.
2. Whether the political question doctrine makes such claims nonjusticiable and deprives Missouri courts of subject-matter jurisdiction.
3. Whether the petition, treated as true at the pleading stage, stated claims under Missouri law sufficient to survive a motion to dismiss.

## Decision

- The Missouri Court of Appeals reversed the trial court’s dismissal and remanded for further proceedings.
- The court held that federal regulation of nuclear safety did not bar state-law damages claims based on traditional tort theories where plaintiffs sought compensation for alleged property damage rather than state control of nuclear operations.
- The court rejected Mallinckrodt’s political question argument, concluding that ordinary tort claims for property damage present judicially workable standards and may be heard in state court.
- Because the jurisdictional bars asserted by Mallinckrodt did not apply, dismissal at the pleading stage was improper.

## Legal Principles

- In the nuclear energy area, state law is displaced when Congress has occupied the field of safety regulation; however, federal law does not necessarily eliminate state tort remedies for damages.
- A common formulation for nuclear-field preemption asks whether (1) there is an irreconcilable conflict between federal and state standards, or (2) applying a state standard would frustrate federal objectives.
- Following *Silkwood v. Kerr-McGee Corp.*, state-law damages actions may proceed even in a heavily federally regulated nuclear setting, so long as they do not function as an attempt by the state to set nuclear safety requirements.
- The political question doctrine does not bar adjudication of traditional tort disputes merely because the defendant’s activities are subject to federal nuclear regulation; courts can decide causation and damages without making policy choices assigned to the political branches.
- On a motion to dismiss, courts accept well-pleaded factual allegations as true and do not resolve disputed facts about emissions, causation, or extent of harm at the pleading stage.

## Conclusion

The Missouri Court of Appeals held that Maryland and Bennett’s tort suit seeking damages for alleged property harm from Mallinckrodt’s low-level radiation emissions was not barred by federal preemption or the political question doctrine, and it reversed the dismissal and remanded for litigation on the merits.


Maryland Heights Leasing, Inc. v. Mallinckrodt, Inc., 706 S.W.2d 218 (1985)